New Thermocell Could Harvest 'Waste Heat' from Power Stations and Even Vehicle Exhaust Pipes

8:59 am

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Thermocell harvest waste heat

A small team of Monash University researchers working under the Australian Research Council (ARC) Centre of Excellence for Electromaterials Science (ACES) has developed an ionic liquid-based thermocell. Thermocells are based on harnessing the thermal energy from the difference in temperature between two surfaces and converting that energy into electrical energy.

Led by Monash University researcher and Australian Laureate Fellow Professor Doug MacFarlane and Monash University PhD student Theodore Abraham, the collaborative project developed the thermocell device with the highest power outputs yet reported and no carbon emissions.

The new thermocell could be used to generate electricity from low grade steam in coal fired power stations at temperatures around 130°C. This would be implemented by having the steam pass over the outer surface of the hot electrode to keep it hot while the other electrode is air or water cooled.

Professor MacFarlane said the breakthrough included the development of a novel ionic liquid-based redox electrolyte.

"We have found that it can work at elevated temperatures typical of important heat sources, as opposed to water-based systems, which cannot operate at temperatures above 100 degrees Celsius," Professor MacFarlane said.
"The device offers the possibility of a cheap and flexible design suitable for harvesting waste heat in the 100- to 200-degrees Celsius range."

PhD student Theodore Abraham said that by using heat already produced in industrial processes that would otherwise be untapped, the thermocell is an attractive method of relieving some of the present reliance on fossil fuels.

"The major benefit of a thermocell is that it harnesses energy that is already readily out there; you're just harnessing energy that is otherwise lost to surroundings," Mr Abraham said.
Mr Abraham was supervised by Dr Jenny Pringle of Deakin University who said the development was a significant achievement for a PhD student.

"The advance we made with this system was that we are generating more electrical energy than any previous power cell in this temperature range," Dr Pringle said.
ACES Director Professor Gordon Wallace said that it took a multitude of skills to tackle complex issues as encountered here.

"Our unique research environment within ACES provides an opportunity to acquire these skills in a cutting edge research environment," Dr Wallace said.


Mr Abraham's research is published in the journal Energy and Environmental Science.

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'Power Plants': How to Harvest Electricity Directly from Plants

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Power Plants

May 9, 2013 — The sun provides the most abundant source of energy on the planet. However, only a tiny fraction of the solar radiation on Earth is converted into useful energy.

To help solve this problem, researchers at the University of Georgia looked to nature for inspiration, and they are now developing a new technology that makes it possible to use plants to generate electricity.

"Clean energy is the need of the century," said Ramaraja Ramasamy, assistant professor in the UGA College of Engineering and the corresponding author of a paper describing the process in the Journal of Energy and Environmental Science. "This approach may one day transform our ability to generate cleaner power from sunlight using plant-based systems."

Plants are the undisputed champions of solar power. After billions of years of evolution, most of them operate at nearly 100 percent quantum efficiency, meaning that for every photon of sunlight a plant captures, it produces an equal number of electrons. Converting even a fraction of this into electricity would improve upon the efficiency seen with solar panels, which generally operate at efficiency levels between 12 and 17 percent.
During photosynthesis, plants use sunlight to split water atoms into hydrogen and oxygen, which produces electrons. These newly freed electrons go on to help create sugars that plants use much like food to support growth and reproduction.

"We have developed a way to interrupt photosynthesis so that we can capture the electrons before the plant uses them to make these sugars," said Ramasamy, who is also a member of UGA's Nanoscale Science and Engineering Center.
Ramasamy's technology involves separating out structures in the plant cell called thylakoids, which are responsible for capturing and storing energy from sunlight. Researchers manipulate the proteins contained in the thylakoids, interrupting the pathway along which electrons flow.

These modified thylakoids are then immobilized on a specially designed backing of carbon nanotubes, cylindrical structures that are nearly 50,000 times finer than a human hair. The nanotubes act as an electrical conductor, capturing the electrons from the plant material and sending them along a wire.

In small-scale experiments, this approach resulted in electrical current levels that are two orders of magnitude larger than those previously reported in similar systems.

Ramasamy cautions that much more work must be done before this technology reaches commercialization, but he and his collaborators are already working to improve the stability and output of their device.

"In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run," he said. "If we are able to leverage technologies like genetic engineering to enhance stability of the plant photosynthetic machineries, I'm very hopeful that this technology will be competitive to traditional solar panels in the future."

"We have discovered something very promising here, and it is certainly worth exploring further," he said. "The electrical output we see now is modest, but only about 30 years ago, hydrogen fuel cells were in their infancy, and now they can power cars, buses and even buildings.

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